A systematic experiment based development of a kinetic model for the immobilized lipase (Novozym 435) catalyzed hydrolysis of a short-chain fatty acid methyl ester mixture in a biphasic organic-aqueous system was conducted. It included kinetic experiments to find the influence of the operating conditions on the reaction rate, the examination of the catalyst wetting and of the liquid-liquid phase behavior, as well as the formulation of an integral mathematical model for the used packed-bed reactor assembly. From experiments it was found that the initial reaction rate was independent of the total water content and directly proportional to the catalyst to organic phase mass ratio. The produced fatty acids and methanol reduced the reaction rate reversibly. During the experiments no negative impact on the enzyme activity was observed for temperatures <65 degrees C. The organic phase retained in the particle pores and around the particle prevented the aqueous phase from penetrating it. The influence of the aqueous phase pH-value on the reaction rate was negligible. A good description of the liquid-liquid phase behavior was obtained from a UNIFAC (Dortmund) and literature data based UNIQUAC model. For the reaction rate and the chemical equilibrium activity based expressions were chosen. The very good consistency of the resulting kinetic model with the experimental data confirmed the ability of the chosen approach to elucidate the relationships between the singular effects simultaneously occurring in the reaction system. (c) 2011 Elsevier Ltd. All rights reserved.